(CNN) — Nearly a minute has passed yet the sea in front of us remains still, save for a ring-shaped life preserver bobbing upon its surface.
Inside it is a mesh net, known as a sukari, filled with red, yellow and black sea cucumbers, and in the background beyond, a jagged hillside covered with trees. Just as I start getting nervous she appears, popping her cloth-covered head out of the water and exhaling her breath with a sharp whistling sound.
Back on our fishing boat, Captain Masumi Nakamura points to the woman and says proudly in Japanese: "My wife Sayuri is the best and fastest ama out there. She can catch as many as six abalone in one underwater dive."
Sayuri Nakamura, 64, is part of a team of five female ama divers that hunt for seafood almost daily in the waters in and around Toba City in Japan.
Depending on what the local Ama Association designates that day, they spend between 1.5-2 hours each morning in the sea, free-diving for everything from sea cucumbers, seaweed and turban shells to their prize catch: abalone.
Sayuri and her husband have been working alongside one another since she was 19 -- the same year she started diving.
"My number one condition when marrying was that the woman be an ama diver," says Masumi, who comes from a long line of fishermen. "This way we could spend our days together."
As the ama divers descend, their fins are the last thing to disappear into the sea.
A centuries-old tradition
The tradition of ama diving dates back centuries, with references to these "women of the sea" first recorded around 5,000 years ago.
While the industry was once thriving, today only about 2,000 ama divers remain in Japan.
About 800 of them -- including Masumi's team -- reside in the Ise-Shima area of Japan's Mie prefecture, a region especially known for its rich waters. Like Sayuri, many of these women are in their 60s and have been diving their entire adult lives.
Japan's female ama divers are the stuff of legend.
It was in the years following World War II that many Westerners first learned of these real-life mermaids -- who in those days wore nothing more than a loincloth and diving mask, and a bandana to protect their heads during dives.
Their uniforms later switched to a more modest cloth shirt and pants before the women began donning full rubber wetsuits after 1960.
Ocean whistles and fish days
Masumi has taken us to the calm waters of a sheltered cove for this morning's dive -- though the team often operates in open ocean waters.
All around us the ama's heads pop out of the water, each one then swimming back to their sukari -- attached to their bodies by a rope --before diving gracefully underwater again. As they go, their blue, yellow and green fins are the last things to disappear into the sea.
We learn that the whistling noise they emit when resurfacing is called isobue, or "ocean whistle," which helps regulate their breathing.
The entire free-diving process allows ama to develop an extremely large lung capacity -- a characteristic that many then pass along to their kids.
In fact, Sayuri's 91-year-old mother was an ama diver, finally retiring at age 70.
Unlike ama in other parts of Japan, where the women dive for multiple hours twice daily, Masumi and his team dive only once a day, usually six days a week.
Saturdays are their days off, along with two Tuesdays a month they refer to as "fish day." This gives young fishermen a chance to meet women, says Masumi.
Still, the work is intense, but it also frees up time for the ama to spend with their families and give back to their communities. Sayuri's younger sister Yoshino -- also on Masumi's team -- operates a dry seafood store, while Masumi runs a hotel.
On reaching port the divers haul their buckets to a market where the catch is sorted and weighed.
No territorial disputes here
As the women continue to dive, Masumi takes us on a trip around the cove to enjoy the surrounding scenery. On a beach we spot several ama divers walking into the sea; a line of mopeds parked along a nearby road.
They are kachido-style ama, Masumi tells us. Basically this means they're freelance divers, using their own foot power to propel them into the water and searching for their catch at swallower depths -- approximately 16-26 feet (about 4-8 meters).
Masumi and his team are funado-style -- using a boat (dubbed a totokakabune, or "papa mama boat," because husbands and wives often work together) so they can dive even deeper, typically from 33-50 feet in depth.
To do so, funado ama tie heavy weights around their waists that help them descend quicker. While many teams often dive in the same general area at once, neither infiltrates the other's territory. Masumi says it's an unwritten rule.
We return to the dive site where Sayuri and the others climb back onto the boat hauling her day's catch.
They then place them into individual buckets -- each labeled with the diver's name -- as we head back toward shore. The women sit laughing and chatting about the day's conditions, all wondering who will have scored the largest catch.
This daily bet is nicknamed the "50 second battle," and Sayuri is typically the winner. "Otherwise she won't talk to us," says Yoshino, laughing.
Once reaching port, the divers haul their buckets to their association's nearby market, where the catch is then sorted and weighed. It's here that they will find out how much money they made that day -- a moment that's both exciting and nerve-racking.
Afterward, the women head off to their ama goya, or hut, to light a fire, warm their bones and snack on freshly caught treats, including sea urchin and turban snails.
It's a routine they know well, and one these particular five divers wouldn't trade for anything.
How to experience Japan's ama culture
Hachiman-Kamado Ama Goya, Toba City: Enjoy fresh seafood prepared and served by traditionally dressed ama divers in an ama goya-style eatery, learning about their diving methods, history and culture while you dine. More info at Amakoya.com. Toba Sea-Folk Museum: An architecturally stunning space that features a short film on Japan's ama divers, along with a full exhibit highlighting the unique trade. More info at Umihaku.com. Mikimoto Pearl Island, Toba City: Offers ama diving demos 8-9 times daily to commemorate their role in pearl cultivation. More info at Mikimoto-pearl-museum.co.jp. Shirongo Matsuri Ama Festival,Toba City: Every July, ama divers wearing white isogi outfits compete to see who can catch one pair of male and female awabi -- or abalone -- the quickest. More info at Tobakanko.jp/en.